Subfloating mine



Dec. 5, 1961 J. D. TURLAY ET AL 3,011,438

SUBFLOATING MINE Filed Jan. 24, 1944 9 Sheets-Sheet 1 :2 J 27. J'urZay JRWYZWMHIJ Dec. 5, 1961 J. D. TURLAY ETAI. 3,01 38 SUBFLOATING MINE Filed Jan. 24, 1944 9 Sheets-Sheet 3 9 D. TurZay JZWZbwnsezuZ Dec. 5, 1961 J. D. TURLAY ETAL SUBFLOATING MINE 9 Sheets-Sheet 4 Filed Jan. 24, 1944 a 1 1/0 wt 0w J D. Y'urlay JZWJ'ownsend 7/ mmig WWW:

Dec. 5, 1961 J. D. TURLAY ET AL 3,011,438

SUBFLOATING MINE 9 Sheets-Sheet 5 Filed Jan. 24, 1944 248 242 dun: mrlw unm- gwua/wbow J D. Zurla 1?.W1bwnsend Dec. 5, 1961 J. D. TURLAY ETAL SUBFLOATING MINE 9 Sheets-Sheet 6 Filed Jan. 24, 1944 gvwe/rvb w JD. Turlay 1i? .WTownsend Dec. 5, 1961 J. D. TURLAY ETAL SUBFLOATING MINE 9 Sheets-Sheet '7 Filed Jan. 24, 1944 Ema 'III/I'IIIIII IY$165 we SYWQ/YM I JD. Turla lilWTowns iul y/ gm Dec, 5, 1961 J. D. TURLAY ET AL 3,011,438

SUBFLOATING MINE Filed Jan. 24, 1944 9 Sheets-Sheet 8 JD. Turlay JZWJbwnsend ,i I m 7/ fizmz Dec. 5, 1961 J. D. TURLAY ETAL 3,011,438

'SUBFLOATING MINE 3,011,438 UBFLOATENG MINE Joseph D. Turlay, 4536 N. Chelsea Lane, Bethesda, Md, and Richard W. Townsend, l Miirnarson Place NW., Washington, DJC.

Filed Jan. 24, 1944, Ser. No. 519,418

19 Claims. (Cl. 102-14) (Granted under Title 35, US. Code (1952), sec. 266) depth of submersion and the specific gravity thereof is adjusted automatically to the specific gravity of the surrounding water, in which the arming of the mine is delayed until a predetermined degree of adjustment of the specific gravity thereof has been effected, and in which an inertia controlled mechanism is employed to fire the mine in response to a shock or sustained lateral movement of predetermined character received by the. mine.

It has been the general practice in devices hitherto proposed for effecting an oscillating movement of a subfloating body to adjust the specific gravity of the body to a value either greater or less than the specific gravity I of the surrounding water, as the case may be, and to employ a screw propeller controlled by a hydrostat for reversing the movement of the subfloating body caused by the unbalanced condition of the specific gravity thereof. Still another device of this general character such, for example, as the Depth Regulating Device for Subfioating Bodies described and claimed in the copending application of Charles Moon and Raymond L. Driscoll, Serial No. 425,718, filed January 6, 1942, provides an arrangement in which the volume displacing mechanism is set into operation only when a predetermined number of revolutions of the screw propeller have been made and in which the specific gravity of the subfloating body is adjusted progressively by increments during successive oscillations of the body until the specific gravity of the body has been brought to equality with the specific gravity of the surrounding water.

The device of the present invention provides means for causing a subfloating body to oscillate by impulses received from a screw propeller during the time the body has passed the upper and lower control levels of oscilla tion respectively, in which the specific gravity of the body is automatically adjusted to the specific gravity of the surrounding water by varying the quantity of ballast fluid within a ballast chamber while the screw propeller is in operation and in which the ballast fluid propelling mechanism is continuously operated during the entire time the screw propeller is rotating, means being provided for rendering the fluid propelling mechanism inelfective to cause a change in the specific gravity of the body until a predetermined number ofrevolutions of the screw propeller has been made following a reversal in the direction of rotation of the propeller. Furthermore, the device of the present invention is adapted to reduce both the amplitude and frequency of oscillation of the body and the drain on the source of power as the specific gravity of the mine is adjusted to the specific gravity of the surrounding water during successive oscillations of the body.

It has been found that the density of the water varies in accordance with the depth of the water from the surface thereof, the water increasing in density as the dis- 3,911,438 Patented cc. 5, 1%61 tance from the surface of the water is increased. It is thought that this increase in density is due, generally, to the eflect of temperature of the water, the water near the surface usually being warmer than water at a greater depth and, since the temperature of a body of water is continually changing as the result of tidal currents or changes in climatic conditions and difierences in atmospheric temperature such, for example, as occurs between the conditions of day and night, it has been found necessary to provide means for continually compensating for the changes which occur in the temperature of Water from any of the above causes, and for changes in' density due to the degree of salinity of the water in order that a subfloating body may be maintained in a state of oscillation about a predetermined depth of submergence therein with a minimum consumption of energy required to maintain such oscillation.

The system of the present invention is particularly suitable for use with amarine mine of the type adapted to be planted from an aircraft in flight in which the firing of the mine is brought about by an electroresponsive detonator' adapted to be moved to an operative position with respect to an explosive booster charge by the pressure of water against a hydrostatically controlled extender device operatively connected thereto and in which the premature movement of the detonating device from a safe position is prevented prior to the planting of the mine by an arming wire having one end thereof secured to the aircraft and adapted to be detached from the hydrostat device as themine falls away from the aircraft. When the pressure of the surrounding water has been increased sufliciently to cause the detonator to be moved to an armed position with respect to the aforesaid booster charge, a switch mechanism is actuated by the detonator extender mechanism thereby setting into operation a motor controlling the screw propeller and volume chang-, ing mechanism and thereby causing the mine to be set into oscillation about predetermined limits of depth control. The propelling mechanism has connected thereto a pump adapted to force a fluid outwardly froma closed container within the mine or to cause sea water to flow inwardly into the container, as the case may be, after the screw propeller has made a predetermined number of revolutions in either of the two directions of rotation in excess of the number of revolutions of the propeller in the opposite direction. The direction of movement of the fluid within a duct or tube connecting the container with the surrounding water is controlled by a two-way valve mechanism which permits a flow of fluid therebetween when the propeller has made a predetermined number of revolutions in one direction in excess of the number of revolutions of the propeller in the opposite direction and which provides for a by-pass between the inlet and outlet connections of the pump during the time the pump is ineffective to cause a flow of fluid between the container and the surrounding water while the pump is operated. v

The firing mechanism for the aforesaid mine comprises a plurality of electroresponsive devices cbntro'lledby a,

new and improved inertia operated device adapted to close a pair of normally open firing contacts when the inertia device receives a lateral blow of sustained duration, such for example, as may be caused by a vessel colliding with a mine or the mine is suddenly moved laterally by the motion of the water about the moving vessel and in which the premature olosing of the aforesaid contacts in response to oscillatory or relatively slow translational movement of the'mine as'a result of wave action of the water is prevented, as will more clearly appear as the description proceeds. The firing. mechanism is also adapted to fire the mine when the battery controlling the propelling mechanism is exhausted such that the motor M can no longer be operated thereby. Furthermore, the mine is constructed throughout in such a manner as to withstand the heavy blow or shock of impact received as the mine strikes the surface of the water when dropped from an aircraft flying at a considerable altitude, the construction and ruggedness of the parts comprising the mine and the firing mechanism therefor being suflicient to obviate the necessity for employing a parachute to retard the flight of the mine through the air along a path of travel controlled by a plurality of fin members secured to the tail of the mine as the mine drops within a selected target area. Furthermore, the mine is provided with a plurality of detachable ballast devices whereby the mine may be employed with equal effectiveness in fresh water or salt water, as the case may be.

One of the objects of the present invention is the provision of new and improved means for controlling the oscillation of a subfloating body in which the specific gravity of the body is continuously maintained in equality with the specific gravity of the surrounding water by selectively controlling the direction and rate of flow of a ballast fluid.

Another of the objects is to provide means for applying impulses in opposite directions to a subfloating body respectively at predetermined depths of submergence thereby to cause the body to oscillate without a change in the specific gravity of the body when the specific gravity of the body has been adjusted to equality with the specific gravity of the surrounding water progressively by steps corresponding respectively to a predetermined difference in the number of revolutions of the impulse applying means in each of the two directions of movement thereof.

Another object is the provision of new and improved means for causing a subfloating body to be continually submerged in close proximity to a predetermined depth of submersion of the body.

Another object is the provision of a new and improved freely subfloating mine adapted to be fired by a blow received by the mine or by a sudden lateral movement of predetermined character while the mine is floating at a predetermined depth of submersion.

Another object is to prevent the operation of an inertia controlled firing mechanism for a subfloating mine in response to a countermine shock.

Another of the objects is the provision of a new and improved inertia controlled firing member for a floating mine and adapted to fire the mine in response to a disturbance in the surrounding water of predetermined character caused by a vessel in which the premature firing of the mine as the result of wave action is prevented.

A further object is the provision of a new and improved freely subfioating oscillating mine in which the arming of the mine is delayed until the specific gravity thereof has been adjusted to substantially the specific gravity of the surrounding water during successive oscillations of the mine.

A still further object is the provision of new and improved means settable at will for controlling the depth at which the mine is to be submerged.

Still other objects, advantages an improvements will be apparent from the following description taken in connection with the accompanying drawings, of which:

FIG. 1 is a sectional view of a mine according to a preferred embodiment of the invention and showing certain of the control units thereof in elevation;

FIG. 2 is an end view of the device of FIG. 1;

FIG. 3 is an enlarged fragmentary view in elevation of the depth control mechanism taken along the line 3-3 of FIG. 1;

FIG. 4 is an enlarged rear elevational View of the depth controlling device taken along the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken along the line 5-5 of 4 FIG. 3 showing the pressure responsive element in an initial position;

FIG. 6 is a view similar to FIG. 5 showing the pressure responsive element in an extended position;

FIG. 7 is a view partly in section and partly broken away of the propelling and the fluid ballast control mechanism employed with the mine of FIG. 1;

FIG. 8 is a side view of the device of FIG. 7;

FIG. 9 is a vertical sectional view taken substantially along the line 9-9 of FIG. 8;

FIG. 10 is a sectional view taken along the line 10-10 of FIG. 7;

FIG. 11 is a sectional view taken along the line 11-11 of FIG. 7;

FIG. 12 is a view partly in section and partly broken away of the fluid ballast control valve mechanism showing the valve in a neutral position;

FIG. 13 is a view similar to FIG. 12 showing the valve in an open position whereby the ballast fluid is adapted to be forced outwardly from the mine by the pump;

FIG. 14 shows the valve in an open position whereby the ballast fluid is adapted to be forced into the ballast chamber;

FIG. 15 is a view of a pump suitable for use with the present invention with the cover removed;

FIG. 16 is a sectional view of the reduction gear mechanism and associated elements and showing the motor in elevation;

FIG. 17 is a sectional view taken along the line 17--17 of FIG. 16;

FIG. 18 is a fragmentary plan view of the inertia controlled firing mechanism and supporting means therefor;

FIG. 19 is a sectional view of the inertia controlled firing mechanism taken a ong the line 1919 of FIG. 18;

FIG. 20 is a plan view partly broken away of the firing contacts and supporting means therefor with the casing removed;

FIG. 21 is an enlarged bottom plan view of the supporting plate for the inertia controlled firing mechanism and the circuit controlling devices mounted thereon;

FIG. 22 is an enlarged fragmentary sectional view of the detonator extender mechanism and the switch device controlled thereby;

FIG. 23 is an enlarged plan view showing a portion of the mine casing in section and one of the ballast devices detachably secured thereto;

FIG. 24 is a sectional view taken along the line 2424 of FIG. 23; and,

FIG. 25 is a diagrammatic view of an arrangement of the electrical circuits and depth controlling and firing mechanisms employed therewith suitable for use with the mine of FIG. 1.

Referring now to the drawings on which like numerals of reference are employed to designate like parts through out the several views and more particularly to FIGS. 1 and 2 thereof on which is shown a mine indicated generally by the numeral 10 comprising a casing 11 having an end portion 12 secured thereto and provided with an aperture 13 adapted to allow the introduction of an explosive charge 14- composed of TNT, torpex or the like disposed within an explosive chamber 15 formed by a wall or partition 16 extending laterally across the casing and secured interiorly thereto in any suitable manner as by welding the parts together. The aperture 13 is adapted to be sealed by a cover or cap 17 secured thereto as by the bolts 18, a suitable gasket 1? being arranged between the cover and the end portion 12 to insure a watertight joint therebetween.

There is also provided within the casing of the mine a well 21 extending inwardly into the chamber 15 and having a receptacle 22 secured thereto within which is arranged an explosive booster charge 23, the receptacle being preferably braced to the casing of the mine as by the member 24. The well 21 is provided with a shoulder or flange 25 to which is secured as by the bolts 26, a

detonator extender mechanism indicated generally by the numeral 27, a watertight connection between the extender mechanism and the casing of the mine being maintained preferably by a gasket 28 arranged between the extender mechanism and the aforesaid shoulder 25. The partition 16 is provided with a recessed portion 29 having side walls in substantial alinement with the casing 31 adapted to receive and support a battery 32, a suitable wrapping of insulating material 33 being disposed between the battery and the casing in the manner illustrated to maintain the battery securely in a fixed position with respect thereto. The battery 32 is enclosed by a cover 34 secured thereto as by the screws 35, a resilient pad or cushion 36 of material suitable for the purpose such, for example, as rubber being preferably arranged between the cover and the battery.

There is also provided within the casing of the mine a circular support 37 to which is secured as by the bolts 38 a plate or base 39 having secured thereto as by the resilient mountings 41, an inertia controlled firing mechanism indicated generally by the numeral 42 arranged in substantial coincidence with the center of free rocking movement of the mine within the water. ,Supported by the plate 3 in any suitable manner are a plurality of control relays and thermal devices for arming the mine, controlling the operation of the depth control mechanism and for firing the mine in response to the operation of the inertia controlled mechanism 42 as the mine is subjected to lateral movement of predetermined character such, for example, as may be caused by the impact of a vessel striking the mine or relatively sudden movement of the Water caused by the moving vessel, or in the event that the supply of power required to maintain the mine at a predetermined depth of submersion has been exhausted. The firing of the mine in response to a countermine shock received through the surrounding water is prevented by the resilient mountings 4i which reduce the movement of the firing mechanism 42 sufliciently to prevent the operation of the firing mechanism.

There is also secured to the plate 39 a switch 43 having a movable control element 44 adapted to be actuated from the exterior of the mine casing when a detachable plug 45 provided in the casing of the mine in substantial alinement with the control element 44 has been removed. The switch 4-3 is operated momentarily prior to the launching of the mine thereby to insure that the various electroresponsive elements comprising the firing and depth control circuits are in a predetermined initial condition before a cycle of operations thereof is performed, as will more clearly appear as the description proceeds. The inertia controlled firing mechanism and the aforesaid electroresponsive devices are protected during the assembly, testing and transportation of the firing and depth control mechanism by a plate 46 and a pair of brackets 47, the plate and brackets being disposed respectively below and above the plate and secured thereto by the bolts 43.

There is also provided within the casing 11 a recess or well 49 within which is disposed a hydrostatically controlled depth regulating device indicatedgenerally by the numeral 51 secured in watertight relation with respect to the casing of the mine as by the nuts 52 and gasket 53. The device Si is adapted to apply a control tothe depth regulating circuit by way of the conductors within the cable 54 selectively in accordance with the instant depth of submersion of the mine within the water.

The tail of the mine is enclosed by a casing 55 comprising an upper portion 56 and a lower portion 57 secured thereto in any suitable manner as by weldingthe parts together and provided with an annular member 58 secured exteriorly thereto. There is provided on the tail portion of the casing 11 an annular member 59 to which the member 58 is secured as by the bolts 61 and maintained in watertight relation with respect thereto as by the gasket 62. The lower portion 57 of the casing is provided with an aperture 63 adapted to be enclosed by a plate 64 secured thereto as by the bolts 65, a watertight connection being insured therebetween by a gasket 66. Secured to. the lower portion of the plate 64 is a cup-shaped casing 67 adapted to support a reversible motor 68 secured thereto as by the bolts as, the electrical power required for the operation of the motor being supplied thereto by way of the conductors within the cable '71. The motor is adapted to drive a screw propeller 72 at a reduced rate of speed by means of the provision of a reduction gearing within the cup-shaped casing 67. The upper portion 56 of the casing is provided with a cupshaped member 73 secured thereto as by welding the parts together and preferably additionally braced to the portion 56 of the casing as by the annular support 74. The screw propeller 72 is secured to the shaft 75 by a nut 76, the shaft 75 also causing the actuation of a rotary pump within the support 77 thereby to effect a variation in the specific gravity of the mine in accordance with the extent of operation of the pump during the time that the valve indicated generally at 78 has been moved to an open position thereby to establish communication between the pump and the tubes or ducts 79 and 81.

The casing 55 is partly filled with a ballast fluid suitable for the purpose such, for example, as a fluid composed of one part of lard oil and three parts of kerosene adapted to be forced outwardly through the tubes 81 and 79 by the aforesaid pump into the surrounding water or adapted to be supplied with a quantity of water drawn inwardly through the tubes 79 and 81 by the pump, as the case may be, the direction of flow of the fluid being controlled by the direction of operation of the pump during the time the valve 73 is open, as will more clearly appear as the description proceeds. The tube 81 is provided at the lower end thereof with a ball check valve disposed within the casing 82 in communication with the ballast fluid, means being provided to permit the flow of fluid in either direction past the ball valve when the pump is in operation, the direction of movement of the fluid past the valve being controlled by the direction of rotation of the pump. The outer end of the tube '79 is secured to the cap 56 at a nipple 83, a watertight joint between the tube and the nipple being effected by the coupling 84. The nipple is preferably threaded to receive an external connection whereby the pump may be primed, if desired, prior to the launching of the mine. There is arranged on the exterior portion of the casing 5s a plurality. of brackets 85 adapted to support a cup-shaped annular member 86 having a strainer 87 arranged across 'the opening thereof thereby to exclude the entrance of foreign sea growths and the like from the ballast control system.

Secured to the casing 56 in any well known manner as by welding the parts together are a plurality of fins 88 preferably composed of sheet metal having bentover portions adapted partially to enclose the fins at 89 and 91. Supported by the fins incoaxial relation with respect to the shaft 75 is preferably provided a cylindrical member 92 adapted to reduce the turbulence of the water as the screw propeller operates. The ballast fluid is introduced within the casing through a filler hole 93 adapted to be sealed by the plug 94, the filler hole preferably being arranged adjacent the valve 78 whereby the operation of the valve '78 may be made manifest during the testing of the device.

The casing 11 is preferably reinforced by the circular members 95 and 96, the member 96 being adapted to receive and support a plurality of weights 97 detachably secured thereto as by the bolts 98. When it is desiredto plant the mine in a body of salt water, the weights are secured to the member 96 and themine'is thus roughly adjusted to a specific gravity substantially equal to the specific gravity of the salt Water within which the weights being of sufficient mass to render the specific gravity of the mine substantially'the same as the specific gravity of fresh water when the weights are removed,

the mine is to be planted, l

whereby the mine is also adapted to operate with equal facility in either fresh water or salt water. By providing a plurality of detachable weights 97 in the manner disclosed, the mine is adapted to float at a predetermined depth of submersion in either salt water or fresh water, as the case may be, controlled by the setting of a single depth control dial it being merely necessary to remove the weights when the mine is to be planted in fresh water.

The explosive charge 14 is preferably poured into the explosive chamber 15 in a liquefied condition through the aperture 13 when the mine is arranged with the aperture uppermost. The aperture is then sealed by the cap 17 and the mine is turned over with the cap lowermost. The explosive charge solidifies in the position shown in FIG. 1 in close engagement with the dome-shaped end portion 12 of the mine casing and in contact with the lower portion of the recessed portion 29 of the partition 16. An arrangement is thus provided whereby, by employing a dome-shaped cap for the leading end of the mine casing, the mine is adapted to withstand the violent shock of impact of the mine against the surface of a body of water when the mine is launched from an aircraft in flight, without damage or injury thereto, the explosive charge being employed additionally to support the partition 16 and absorb the shock of impact of the battery 32 against the partition as the mine strikes the water.

The detonator extender mechanism 27 will best be understood by reference to FIG. 22, the extender mechanism comprising a casing 99 having a flanged portion 101 adapted to be secured to the shoulder 25 of the mine casing by the bolts 26, FIG. 1. The casing 99 has secured thereto as by the screws 102 an extension member 103 having a flanged portion 104 thereon adapted to maintain the receptacle containing the booster charge in predetermined fixed relation with respect to the extender mechanism when the extender mechanism is in the assembled position within the mine casing. Slideably disposed within the member 103 is a plunger 105 adapted to support an electroresponsive detonating device 106 and move the detonating device from a safe position to an armed position in operative relation with respect to the aforesaid booster charge in response to the pressure of the surrounding water when the mine has reached a predetermined depth of submergence therein. The detonator is provided with a pair of flexible conductors 107 secured at one end thereof and in electrical connection with terminals on a terminal block 108 attached to the extension member 103 as by the screws 109, the member 103 being provided with a suitable slot within which the conductors 107 are disposed thereby to facilitate the movement of the detonator into the armed position. The plunger 105 is provided with a slotted portion 111 within which is arranged a spring 112 adapted to urge a latch 113 outwardly and lock the detonator in an extended or armed position as the latch moves outwardly into the slotted portion 114 of the extension member 103. The member 103 is also provided with an aperture 115 whereby the latch 113 may be moved at will to the retracted position by a suitable tool inserted within the aperture 115 and the detonator extender mechanism may be moved from the armed position to the initial unarmed position, as may be required during the assembly and test of the extender mechanism.

A cup-shaped member 116 is arranged about the plunger 105 thereby to guide a spring 117 disposed thereabout and maintain the axis of the spring substantially coincident with the axis of the plunger 105. The other end of the spring 117 is in registered engagement with the bottom of a slideable cup-shaped member 118 employed for maintaining a flexible diaphragm 119 against a shoulder 121 on the plunger 105 as the clamping nut 122 is tightened. The outer edge of the diaphragm 119 is secured to a shoulder 123 on the casing 99 and clamped thereto by the clamping ring 124 and washer 125. The casing 99 is provided with a cap 126 secured thereto as by the screws 127 and provided with a plurality of apertures 123 whereby water is admitted to the exterior portion of the diaphragm 119 when the mine has been planted. The plunger is also provided with an aperture within the outer end portion thereof adapted to receive an arming wire 129, the arming wire additionally passing through an aperture 131, FIG. 1, within the cap 126 and extending therefrom to a fixed connection on the aircraft whereby the arming wire is withdrawn from the plunger 105 as the mine falls away from the aircraft. With the arming wire arranged within the plunger 105 in the manner illustrated, inward movement of the plunger is prevented by reason of the provision of a cylindrical stop member 132 disposed about the plunger and in abutting relation with the cap 126 and adapted to be engaged by the arming wire and prevent substantial inward movement of the plunger until the arming wire has been withdrawn. The end of the cap 126 is preferably enclosed by a cover 133 threaded therein, whereby, by removing the cover, the insertion of the arming wire within the aperture 131 of the plunger is facilitated.

There is also secured to the detonator extender mechanism at the extension member 103 thereof a switch device 134 having an actuating element adapted to be moved by a plunger 135 as the plunger 135 is engaged and moved outwardly by the plunger 105 at the end portion 136 thereof during the movement of the plunger 105 to the armed position. The switch device 134 is preferably of the single pole double throw type adapted to transfer a circuit from one contact element to another contact element as the switch operates. The contact elements of the switch 134 are in electrical circuit with certain of the terminals of the terminal block 108 as by the conductors indicated generally at 137 connected thereto.

The hydrostatically controlled depth regulating device 51 comprises a casing 138 having a flanged portion 139 adapted to be secured to the casing of the mine by the nuts 52, the casing being provided with a cover 141 preferably composed of suitable transparent material secured thereto as by the screws 142 whereby the operation of the depth control mechanism may be observed during the testing of the device. Arranged interiorly within the casing is a cup-shaped member 143 secured thereto asby the clamping rings 144 and having an expansible bellows 145 arranged therein adapted to be moved to different settings by the pressure of the water within which the mine is planted, a gasket 146 being provided to maintain a watertight connection between the member 143 and the casing 138. The bellows has secured thereto in any suitable manner a rod or plunger 147 arranged coaxially therewith and having an eye formed in one end thereof for engagement with a retractile spring 148; the other end of the retractile spring being in engagement with a rod 149 rotatably disposed within the screw member 151 and maintained in fixed endwise relation with respect thereto by a pin 152 passing through the rod and engaging the outer end of the screw member 151. The screw member 151 is threaded within the casing 138 and provided with a knob 153 secured thereto and having a pointer 154 thereon for indicating the instant setting of the knob.

The knob is rotatably arranged within a recessed portion 155 within the casing 138 and maintained therein by the ring or dial 156 and screws 157. The dial is provided with a series of indicia thereon corresponding respectively to different depths of submersion controlled by the setting of the pointer 154 with respect thereto. The dial also includes a stop member 158 adapted to coact with the pointer 154 and limit the rotative movement of the knob to one revolution thereof. The screws 157 are respectively disposed within a plurality of armate slots 159 arranged within the dial whereby the dial 9 may be adjusted to a predetermined setting within the limits of movement controlled by the aforesaid arcuate slotted portions in accordance with the tension of the spring 148. The arrangement of the screws and slots is such that the dial may, if desired, be moved through a greater distance than the distance afforded by the slots by removing all of the screws 157 and rotating the dial sufficiently for the screws to engage different ones of the slots respectively. When the desired setting of the dial has been attained, the screws 157 are tightened thereby preventing a change in the setting of the dial.

The setting of the knob is retained by the provision of a spring pressed plunger 161 slideably disposed within the casing 138 and having a rounded or chamfered end adapted to coact with a plurality of closely spaced indents 162 circularly arranged within the knob.

The knob is also provided with a plurality of apertures 163 adapted to permit the flow of water into an annular recessed portion 164 thereof, the water being allowed to flow into the interior of the expansible bellows 145 by reason. of the provision of a plurality of orifices 165 within the screw member 151.

The inner end of the rod 147 comprises a reduced portion 166 and a shoulder 167, the reduced portion 166 being adapted to slide freely within an aperture in a contact spring 163 having a washer 169 of suitable insulating material secured thereto in any suitable manner as by the rivets 171, FIG. 4, the washer 169 being employed to engage the shoulder 167 of the rod 147 and cause the contact spring 168 to bedisengaged from contact 172 and be brought into engagement with contact 173 during the expansion of the bellows as the mine sinks within the water. The contact members 166, 172 and 173 are supported by a base 174 of suitable insulating material secured to the casing 138 as by the screws 175, an external electrical connection to the contact members 168, 172 and 173 being established by way of the conductors within the cable 54 having one end thereof secured to the base 174 as by the clamp 176 and screw 177.

The propulsion and automatic ballast control mechanism of the mine will now be described. As hereinbefore described, the plate 64 supports a cup-shaped casing 67 having a reversible motor 68 secured thereto with the shaft of the motor arranged vertically, the motor hereinafter being designated for the purpose of description, by the letter M. The member 67 has secured thereto as by the bolts 69 a support 178, FIG. 16, having a centrally arranged aperture therein within which the upper end of the motor shaft extends. There is secured to the support 178 as by the screws 179 a speed reducing mechanism indicated generally by the numeral 181 comprising an upper casing 182 and lower casing 183 held together in any suitable manner as by the rivets 184. The lower casing 183 supports a bearing 185 withinwhich is rotatably mounted a stub shaft 186 preferably splined as at 187 for engagement with a complementary splined portion on the motor shaft and having a shoulder 138 thereon for engagement with the end of the bearingmember 185. There is also secured to the shaft 186 as by the pin 18? a gear 191 in engagement with a relatively larger gear 192 journaled within the casings 182 and 183. Secured to the gear 192 as by the pin 193 is a relatively small gear 194 in engagement with a larger-gear member 1% rotatably mounted within a bearing 196 secured to the upper casing 182. From the foregoing, it will be apparent that the gear member 195 is adapted to rotate at a relatively slow rate of-speed with. respect to the speed of rotation of the motor.

Secured to the plate 64 in any suitable manner, as by welding the parts together, is a tubular support 197 having bearings 198 and 199, FIG. 9, arranged therein within which is rotatably mounted a shaft 201, the lower end of the shaft being in splined engagement with the gear member 195 at 262. The upper end of the shaft 261 is provided with a grooved portion within which is arranged a coupling member 293 secured thereto as by the pin 204. The upper end of the bearing 199 is provided with a seat 2115 adapted to be engaged by a washer or packing member 2116 in engagement with a suitable packing 207 disposed beneath a washer 208 with which the end portions of the pin 2114 are in engagement. The lower end of the shaft 2411 is provided with a pin 269 having a cup-shaped member 211 in engagement therewith for applying pressure to a spring 212 and Washer 213 in engagement with the bearing 193 at the seat 214 thereof thereby to apply tension to the shaft 291 and maintain a watertight joint at the seat 205 of the bearing 199. The tubular support 197 is provided with a plurality of apertures 215 above the upper bearing 169 thereby to allow the escape of water which mayenter the mine about the propeller shaft from being forced by the pressure of the surrounding water through the tubular member 197 and thence into the reduction gearing and motor, The upper end of the tubular member 197 is *slideably disposed within a cap 216secured to the support 77 as by the screws 217. The upper end of the support '77 comprises a pair of circular flanges 218 and V,

219 adapted to be fittingly disposed within the cupshaped member 73 and secured to the upper portion 56 of the ballast chamber, the upper end of the flange 218 being provided with a gasket 221 adapted to be clamped by the nut 222 threaded on the support '77 and thereby provide a watertight connection between the support 77 and the casing of the mine. A lock washer 223 is preferably provided between the nut 222 and the cupeshaped member 73 thereby to maintain the support 77 continuously in rigid clamped engagement with the portion 56 of the ballast chamber. The lower flange 2153 of the support '77 is provided with a dowel pin 224- adapted to engage a slotted portion 225 within the cup-shaped member 73 and prevent rotative movement of the support with respect thereto. 7

The support '77 is also provided with a bearing 226 at the upper end thereof within which is rotatably mounted the shaft 75, the lower end of the shaft being journaled at 227 within the support 77 and at 228; within the cap 216. A water seal indicated generally at 230 is also provided to prevent leakage of water between the shaft 75 and the bearing 226. Downward movement of the shaft is prevented by a collar or snap ring 229 secured thereto and in engagement with the inner surface of the cap. 216. The lower end 'of the shaft 75 is suitably slotted to receive the coupling member 263 thereby estab-] lishing an operative connection between the shaft '75 and the shaft 261. The lower end of the shaft also includes a portion 231 of reduced diameter having a rotor 232'secured thereto in any. suitable manner as by the pin 233," the rotor being suitably slotted as at 234 to receive the ends of the pin. I

The lower end of the support 77 has a circular recessed portion 235 therein within which is arranged. a circular disk or pumping element 236 adapted to be rotated by the lobes 237, FIG.- 15, of the rotor 232 at the recessd'portions 238'thereof in succession as the shaft 75 isrotated by the motor 68. The pump also comprises two arcuately shaped recessed portions 239 and 241 in communication with the-recessed portion235 of the. support77,- the recessed portions 239 and 211 being diametrically disposed with respect to the rotor 232 substantially as illustrat'ed. The recessed portion241 is in communication with a duct 242 and, in like manner, the recessed portion 239-is in communicationwitha duct 243 within the support 77 The ducts 242 and'243 terminate in'ports within the cylindrical slide valve 244 adapted to be connected together or to the ducts 245 and 246 selectively in accordance with the position of the valve member 247 with- 1 in the cylindrical bore 248 of the valve casing. Whereas in FIGS. 12 through 14, the ducts 242 and 243 areshown throughout their length in section,- it will be understood that this has been done for the purpose of more clearly illustrating the manner in which the ducts are brought into the cylindrical valve.

The valve member 247 is slideably disposed within the bore 248 and urged normally to the position with respect thereto as shown in FIG. 12 by a spring 249 in registered engagement with the valve casing 251 and secured to one end of the valve plunger by a screw 252 and washer 253. The valve is provided With a pair of recessed portions 254 and 255 separated by a cylindrical portion 256 fittingly slideable within the bore. With the valve in the position shown in FIG. 12, the recessed portion 255 thereof establishes a connection between the ducts 242 and 243 whereby the rotative movement of the pump in either direction is ineffective to cause a change in the liquid ballast of the mine. With the valve in the position shown in FEGS. 13 and 14, the pump is in operative communication With the fluid within the ballast chamber and with the water surrounding the mine and adapted to effect a change of ballast in the mine as the pump operates. The slideable valve member 247 is preferably provided with a plurality of annular grooved portions 257 and 25% arranged about the periphery thereof and adapted to effect a water seal between the slideable member 247 and bore 248. The member 247 is provided with a duct 259 therein in communication with a relatively small orifice 251 thereby to insure a flow of liquid sufiicient to render the grooved portion 257 of the member 247 effective as a water seal by the removal of any air which may seep into the groove.

The end of the valve member 247 is pivotally con nected as at 262 to a link 263, the opposite end of the link being pivotally connected as at 264 to a control member or lever 255. The lever 265 is provided with a slotted portion 266 disposed about a post 267, the opposite end of the lever 265 being adapted to move slideably within a stop member 268 secured to the support 77 as by the screws 269. The lever 265 is also provided with a tab 271 formed thereon and adapted to be engaged by a complementary tab 272 formed on the valve actuating member 273 as the member 273 rotates about the post 267. The post 267 is secured to the support 77 as by the screw 274 and has rotatably mounted thereon a worm wheel 275 in meshed engagement with a worm 276 formed on the shaft 75. The worm wheel 275 is secured to a sleeve 277 about which the actuating member 273 is disposed. The actuating member 273 is frictionally driven by the worm wheel 275 by reason of a friction washer 278 arranged therebetween, the actuating member 273 being maintained in frictional engagement therewith by a washer 279 having a plurality of resilient arms thereon in engagement with the actuating member 273 and having a predetermined tension applied thereto controlled by the snap ring 281 and the washer 282 arranged betwen a snap ring and the resilient Washer 279, the degree of friction between the actuating member 273 and the worm wheel 275 being controlled in any suitable manner as by the thickness of the washer 282.

From the foregoing, it will be apparent that engagement of the tab 271 by the complementary tab 272 of the actuating member 273 causes the valve member 247 to be moved from a closed position to an open position regardless of the direction of movement of the worm wheel 275 as shown on FIGS. 13 and 14 of the drawings. When the worm wheel 275 is rotating in the direction shown in FIG. 13, the upper end of the lever 265 is brought into engagement with the stop member 268 and pivots about the point of contact of the lever with the stop member 268 thereby causing the lower end of the lever 265 to be moved away from the valve casing until arrested by the engagement of the post 267 with the end of the slot 266 within the lever thereby opening the valve to permit the pump to effect a change in the fluid ballast of the mine. When this occurs, additional rotative movement of the actuating member 273 is prevented until the direction of rotation of the worm wheel 275 is reversed. When the direction of movement of the pump is reversed, the worm wheel 275 is rotated in the direction shown on FIG. 14 by the reverse movement of the shaft 75 and the disengagement of the tab 271 with the complementary tab 272 of the actuating member causes the lever 265 to be moved toward the valve casing by the spring 249 until the opposite end of the slot 266 therein engages the post 267 as shown in EEG. l2 and the valve to be closed until the tab 272 again engages the tab 271i. When this occurs, the lever 265 is pivoted about the post 267 as a fulcrum in a direction to open the valve and reestablish an operative fluid connection between the ballast fluid within the mine and the surrounding water. When the upper end of the lever 265 engages the stop member 263 in the manner illustrated in FIG. 14, further rotative movement of the lever 265 and the actuating member 273 is prevented. The worm wheel 257, however, may continue to rotate by reason of the frictional coupling between the worm wheel and the actuating member. It will, of course, be understood that while the worm wheel is moving from the position shown on FIG. 13 to the position shown on FIG. 14, the valve will assume the closed position shown on FIG. 12.

The duct 245 is connected to the tube 81 by the coupling 283, the lower end of the tube 8:. being connected to the casing 82 disposed within the ballast fluid, the connection being established by way of a valve fitting 284 having an aperture 285 therein and a plurality of orifices 2S6 communicating with the interior of the casing 32. Arranged within the aperture 235 is a check valve comprising a ball 287 in seated engagement with a thimble 283 having a flanged portion 289 thereon yieldably maintained in engagement with a seat 291 on the member 284 by a spring 292, the opposite end of the spring being in engagement with a shoulder on a plug member 293 threaded within the fitting 284. There is also preferably provided a screen or perforated disk 294 secured at the central portion thereof by the plug member 293 and washer 295 and secured at the periphery thereof in any suitable manner to the casing 32 thereby to prevent the entrance of dirt or foreign substances within the casing 82. An arrangement is thus provided in which foreign matter in the ballast fluid is excluded from the pump and valves of the ballast control system. 7 There is also preferably provided within the fitting 284 a pin or rod 296 adapted to arrest the upward movement of the ball 237 as fluid is drawn upwardly within the tube 81 by the pump. The casing 32 is provided with a bracing member 297 secured thereto and having an aperture therein of sufficient size slideably to receive the tubular support 197.

The inward flow of water from the sea during the time that the pump is not operated is prevented by a valve mechanism arranged between the duct 79 and the orifice 246 extending to the valve mechanism. As most clearly shown on FIG. 10, the duct 79 is connected to the support 77 as by the coupling 298 whereby communication with the outside water is established to an orifice 299 within the support. Threaded within the support 77 is a guide member 361 having a seat at the lower portion thereof adapted to be sealed by a disk valve 302 yieldably maintained in engagement therewith by the spring 303 thereby to seal the orifice 299 when the valve 302 is in a closed position by reason of the provision of a gasket 3G4 arranged between a shoulder on the member 351 and a complementary surface on the support 77. There is also arranged on the support 77 an expansible bellows 3495 ealed at the lower end thereof to the support as by the gasket 306 and clamping ring 307, a cover 358 having an aperture 3G9 therein being provided to protect the bellows and limit the upward movement thereof. The interior of the bellows is in communication with a recessed portion 311 and thence by way of the duct 246 with the valve memher 247. There is also slideably arranged within the guide member 301 a valve actuating mechanism 312 having a plurality of recessed portions 313 and 314 at the upper and lower ends thereof respectively. The disk valve 3492 is adapted to open in response to a predetermined increase of pressure within the bellows 395 in excess of the pressure of the surrounding Water or in respouse to a predetermined decrease in pressure within the bellows 335 from the pressure of the surrounding water, as the case may be, the operation of the valve 332 in the latter case being accomplished by the contraction of the bellows sufficiently to overcome the spring 393 and the pressure of the surrounding water on the valve 302 by reason of the movement of the valve actuating mechanism 312 by the bellows, as will more clearly appear as the description proceeds.

The inertia firing control mechanism employed with the mine of FIG. 1 comprises a supporting base 315 secured to the plate 3h yieldably as by the resilient mountings 4-1, the mountings 41 being attached to the base and plate in any suitable manner as by the rivets 3-15. The base 315 has a hemispherical portion 317 and a plurality of upturned edges 318 thereby to strengthen the base and increase the resistivity thereof to deformation as the result of the shock received during the planting of the mine. The base 315 is provided with a support 319 secured thereto in any suitable manner as by welding the parts together and having slideably arranged therein a plunger 321, the plunger having a shoulder 322 thereon adapted to be continuously maintained in engagement with a complementary shoulder 323 arranged within the support 319 by a spring 324 at all times except when a heavy shock is received during the planting of the mine. The opposite end of the spring 324 is arranged within a recessed portion 325 of a cap or plug 326 threaded within the support 319. The support 319 extends downwardly within an aperture 327 centrally arranged within the plate 39 whereby the lower portion of the base 315 is normally supported by the resilient mountings 41 at a distance from the curved portion 323 of the plate 39 sutficient for the portion 328 of the plate to be employed as a stop for the base 315 when the base 315 moves into engagement with the portion 328 of the plate 39 as the result of the shock received during the planting of the mine from an aircraft in fiight.

The plunger 321 is tapered as at 32$ thereby to form a conic section upon which is pivotally mounted a mass 331 suitably recessed at 332 to coact with the apex of the aforesaid conic section of the plunger 321 and pivotally support the mass thereon. The mass is of such a shape that the center of gravity thereof is slightly lower than the point of support and sudden translational movement of the plunger 321, therefore, causes the mass 331 to tilt.

The upper surface of the mass 331 comprises a conic recessed portion 333, a circular fiat surface 334 coaxially arranged with respect to the conicrecessed portion and a curved annular surface or seat 335 intermediate the flat surface and the conic recessed portion. A circular member 336 is tapered and rounded as at 337 thereby to coact with the curved annular surface 335 of the mass 33-1 and maintain the member 336 in predetermined spaced relation with respect thereto at all times when the device is not subjected to sudden translational movement of a predetermined character. The member'fal'afi is secured to a circular plate 338 having afcylindrical member 339 secured thereto and extendingboth upwardly and downwardly therefrom substantially as shown. The lower portion of the cylindrical member 339 comprises a laterally extending flanged portion 341 to which is secured as by the screws 342 a circular mass 343 extending downwardly therefrom and having a truncated spherical surface 3% with a radius of curvature sufficiently less than the radius of curvature of the inside surface of the supporting base 315 whereby the shock of planting the mine is adapted to cause the circular mass to engage the inside surface of the base 315 and the mass 331 to be arrested by the mass 343 and the spring 324 to be compressed by the shock received by the mine as the mine strikes the surface of the water, thereby preventing damage or injury to the pivot support 321 at the tapered portion 32$ thereof. The mass 315 is also provided with a tapered recessed portion 34d of sutficient size to permit considerable pivotal movement of the mass 343 as the device receives a translational impulse of predetermined character. In a similar manner the mass 331 is recessed as at 345 to permit tilting of the mass 331 about the pivot support therefor. When the firing mechanism is tilted sufficiently for the recessed portions 344 and 345 of the masses 315 and 333 respectively to engage the slideable support for the. pivot member 321, the members 315 and 331 are tilted with respect to each other sufiiciently to close a pair of firing contacts, as will more clearly appear as the description proceeds.

A structure is thus provided in which the elements 331 and 343 comprise a compound pendulum adapted to oscillate as a unit about the pivot support 3% in response to relatively slow translational impulses received thereby and in which relative motion between the masses 33f and 343 is effected as the result of the lateral component of a blow or sudden impulse of predetermined character received by the device by reason of the center of gravity of the mass 343 and supporting means therefor being disposed at a greater distance below the pivot 332 than the center of gravity of the mass 331 and by reason of the moment applied to the mass 331 by the horizontal compongnt of the force applied thereto by way of the pivot member 321. Rotational movement of the mass 343 and supporting means therefor including the circular member 336, with respect'to the mass 331, causes a plunger 346 slideably arranged within thern'emher 336 to be moved downwardly by the combined force of gravity and tllGlGHSlOil of the contact spring 347 thereagainst. When this occurs, the contact spring 347 is brought into engagement with the contact element 3 38 thereby closing the firing-control circuit comprising the conductors 349 secured thereto. The contact members 347 and 348 are electrically insulated from each other and from the plate 338 as by the insulating devices 351 and 352, the insulating device 352 preferably being provid'ed with an aperture through which the plunger 346 is adapted to move. bers 347 and 34$ is a guard 353 thereby to prevent excessive flexing of the contact members 347 and 348 sulficient to change the adjustment thereof regardless of the violence of the shock to which the device may be subjected. 'The aforesaid guard and contact members are secured to the plate 338 as by the screws 354. Secured to the base 315 as by the screws 355 is a hemispherical cover 356, a gasket 357 being arranged therebetween' thereby to seal the spherical chamber within which the inertia switch contacts are disposed. l

A cylindrical projecting member 358 having the upper end thereof closed at 359 is clamped to the upper portion of the cover 356 as by the nut 361, a watertight connection therebetween being assured by disposed between a shoulderfiefa on the member and a complementary recessed portion 56 Within the cover. The projecting member 358 is composed of insulating material suitable for the purpose such, for example, as

. Bakelite and is provided preferably with a pair" of inserts 365 adapted to receive the screws 366 and thereby establish an external circuit connection to the conductors 349 respectively secured thereto. There is arranged beneath the heads of the screws 366 a plate 367 having a downwardly projecting eye 368 therein adapted to engage and support one end of the spring sea. The other end of the spring 369 issecured to an eyef3'71 formed in the bracket 372 secured to the plate 338 asby the screws 373. An

, arrangement is thus providedin which'the spring 369 is employed to lessen the pressure on the pivot 32:1, prevent excessive rotation of the pendulum about the pivot sup- Disposed about the contact menn.

a gasket 362' 15 port, and apply a restoring force to the elements of the compound pendulum in a direction to assist the force of gravity in restoring the pendulum to an initial vertical position.

The plate 39 is also employed to support a plurality of relays and thermal responsive contact devices employed for controlling the operation of the motor M in response to the selective operation of the hydrostatically controlled depth regulating device 51, a suitable arrangement of the relays and electroresponsive control devices being shown on FIG. 21 in which the relays A, B, C, D, F, R, and TR are preferably located on the underside of the plate and interconnected by means of the conductors within a cable, not shown, securely clamped to the plate 39 as by the cable clamps 374. There is also mounted on the lower portion of the plate 39 a plurality of jacks 375, 376, and 377 adapted to receive plugs associated with flexible cables leading to the hydrostatically controlled depth regulating device, the motor M, the battery 32 and the terminal block 188, FIG. 22, the cable to the terminal block being arranged Within a tube or cable duct 378 extending between the wall 16 and the well 21, FIG. 1. On the upper side of the plate 39, FIG. 21, is preferably arranged the thermal relays K, G, and I and the switch 43, the electrical connections between the electrical devices arranged on the upper and lower portions of the plate 39 being established by the conductors within the insulating bushings 379, 380 and 381 within the plate.

The operation of the mine will now be described. Let it be assumed, by way of example, that the hydrostatically controlled depth regulating device 51 has been set with the pointer thereof opposite the numeral 40 whereby the mine is adapted to oscillate between the control limits of 40 and 46 feet beneath the surface of the water, the lower control level of 46 feet being determined by the additional increase in pressure of the surrounding water necessary to expand the bellows 1 15 by an amount corresponding to the travel of contact 168 between contacts 172 and 173, FIG. 5. Let it further be assumed that a copious supply of ballast fluid has been introduced within the ballast chamber through the aperture 93 within the cap 56 caused by the removal of the plug 94 and that the plug 94 is thereafter assembled within the cap. The nipple 83 is connected to a filler tube thereby establishing an external fluid connection between a container having a quantity of ballast fluid therein and the pump, the strainer 87 being preferably removed sufficiently to establish the external fluid connection to the nipple. The plug 45 is now removed and the push button 44 is operated thereby causing the movable contact element 382 thereof, FIG. 25, to be disengaged from contact 383 and moved into engagement with contact 384 thereby closing a circuit from the positive terminal of battery BA by way of conductor 385, windings of relays A and C in parallel, conductor 386, contacts 172 and 163 of the hydrostat switch, conductor 387, contacts 382 and 334 of switch 43 and thence by way of conductor 338 to the negative terminal of battery BA thereby causing relays A and C to operate. The operation of relay C closes a circuit from the positive terminal of battery BA1, conductor 389, break contact and armature 391 of relay D, conductor 392, armature of motor M, conductor 393, armature 394- and make contact of relay C, conductor 395, field winding 396 of the motor M and thence by Way of conductor 397 to the negative terminal of battery BA1 thereby setting the motor in operation in a direction to pump fluid from the aforesaid container into the ballast chamber. When the motor has operated for a period of time sufiicient to prime the pump, the :switch 43 is released by removing the pressure from the movable element 44 thereof and the contact element 382 is disengaged from the contact 384 and moved into engagement with contact 383. As contact element 382 moves away from contact 384, relays A and C release thereby interrupting at armature 394 of relay C and make contact thereof the operating circuit to the motor and causing the motor to come to rest. The plug 45 is now replaced in the casing of the mine, the filler connection removed from the nipple 83 and the strainer 87 replaced to cover the nipple 83. Let it also be assumed that an arming wire 129 has been assembled within the aperture 131 of the plunger 105, FIG. 22, the arming wire extending through an aperture 128 of the cap 126 and se cured at the opposite end thereof to the aircraft.

As the mine falls away from the aircraft in flight, the arming wire is withdrawn thereby removing the mechanical restraint from the detonator extending mechanism. As the mine strikes the surface of the water, the plunger 321 of the inertia controlled firing device 42 is forced downwardly by the inertia of the masses resting thereon thereby extending the spring 369 and compressing the spring 324 until the circular mass 343 engages the curved portion 328 of the supporting base 315. The mass 331 also moves downwardly into engagement with the mass 343 and is arrested thereby. The contact elements 347 and 348 are momentarily engaged but without effect as the mine is unarmed. Concurrently therewith the supporting base 315 is moved downwardly by the force of inertia and the provision of the resilient mountings 41 into engagement with the curved portion 328 of the plate 39. Damage or injury to the inertia switch and operating means therefor is thus prevented. As the shock received by the mine at the moment of striking the surface of the water abates, the supporting base 315 is moved away from the plate 39 by the resilient supports 41 and the inertia elements are moved by the springs 324, and 369 to the position shown in FIG. 19.

As the mine continues to move downwardly within the water, the pressure of the surrounding water against the flexible diaphragm 119 of the detonator extender mechanism, FIG. 22, causes the plunger thereof to be moved inwardly thereby compressing the spring 117 and moving the detonator 186 into an operative or armed position with respect to the explosive booster charge 23. During the movement of the plunger rod 105 from the initial position thereof to the armed position, the plunger 135 is operated thereby causing the switch 134 to be actuated and contact element 398 thereof, FIG. 25, to be disengaged from contact 399 and moved into engagement with contact 401. As contact 398 of the switch 134 engages contact 481, a circuit is closed from the negative terminal of battery BA by way of conductor 388, contacts 398 and 401 of the extender switch 134, conductor 402, contacts 383 and 382 of switch 43, conductor 387, contacts 168 and 172 of the depth control switch, conductor 386, windings of relays A and C in parallel, conductor 385 and thence to the positive terminal of battery BA thereby causing relays A and C to operate. operation of relay C at armature 394 thereof closes a circuit from the positive terminal of battery BAl, condoctor 389, break contact and armature 391 of relay D, conductor 392, armature of motor M, conductor 393, armature 394 and make contact of relay C, conductor 395, field winding 396 of motor M, conductor 397 and thence to thenegative terminal of battery BA1 thereby causing the motor to run in a direction to drive the mine downwardly and to pump water into the ballast chamber by reason of the pump valve being in the position shown in FIG. 14 as the result of the prior operation of the pump during the priming thereof. The specific gravity of the mine is adjusted initially substantially to the specific gravity of the water in which the mine is to be planted or, if desired, slightly less than the specific gravity of the surrounding water.

When the mine reaches a depth of 40 feet, the bellows is expanded sufficiently for the contact element 168 controlled thereby to be disengaged from contact 172 thereby releasing relays A and C and bringing the motor to rest. As the mine passes beyond the lower control level of 46 feet, the bellows 145 is expanded sufficiently The by the pressure of the water therein to cause contact element 168 to be moved into engagement with contact 173. When this occurs, a circuit is closed from negative terminal of battery BA by way of conductor 388, contacts 398 and 401 of switch 134, conductor 402, contacts 383 and 382 of switch 43, conductor 387, contacts 168 and 173 of the depth control switch, conductor 403, windings of relays B and D in parallel, conductor 385 and thence to the positive terminal of battery BA thereby causing relays B and D to operate. As armature 391 of relay D engages its make contact, a circuit is closed from the positive terminal of battery BA1 by way of conductor 389, break contact and armature 394 of relay C, conductor 393, armature of motor M, conductor 392, armature 391 and make contact of relay D, conductor 395, field winding 396 of motor M, conductor 397 and thence to the negative terminal of battery BA1 thereby causing the motor to be set in operation in a direction to propel the mine upwardly. As the propeller shaft 75 rotates in a direction to propel the mine upwardly, the worm wheel 275 is rotated in the direction shown on FIG. 13 and the pump valve is moved by the spring 249 to the position shown on FIG. 12 during the first few revolutions of the propeller and remains in the position shown on FIG. 12 for a predetermined period of time such, for example, as seconds until the worm wheel 275 has rotated sufiiciently to move the valve to the position shown on FIG. 13, the worm wheel thereafter continuing to rotate without additionally moving the valve by reason of the provision of the frictional coupling between the worm wheel and the valve actuating member 273. While the valve is in the intermediate or closed position shown on FIG. 12, the pump is ineffective to change the quantity of fluid within the ballast chamber but merely circulates water through a by-pass in a direction indicated by the arrows on FIG. 12. As the valve moves to the position shown on FIG. 13 at the expiration of the aforesaid period of time, the pump causes ballast fluid to be forced outwardly from the ballast chamber in a direction indicated by the arrows thereby reducing the quantity of ballast fluid within the chamber and decreasing the specific gravity of the mine.

As the mine traverses the lower control level during the first upward movement thereof, contact element 168 is disengaged from contact 173 of the depth control switch thereby releasing relays B and D and bringing the motor to rest.

As the mine passes above the upper control level, contact 168 of the depth control switch is moved into engagement with contact 172 thereby operating relays A and C, the operation of relay C at armature 394 thereof causing the motor to operate in a direction to propel the mine downwardly. As the propeller starts to rotate, the worm wheel 275 is moved in a direction shown on FIG. 14 thereby closing the pump valve for 10 seconds during which time the pump circulates water through the bypass in a direction reverse to the direction of the arrows on FIG. 12. At the completion of the 10 second period, the valve is moved to the position shown on FIG. 14 and the pump causes sea water to be drawn into the ballast chamber thereby increasing the specific gravity of the mine until the mine passes below the upper control level.

The mine continues to oscillate between the upper and lower control levels and effect changes in the specific gravity of the mine during the travel of the mine beyond each of the control levels when the time of each such travel exceeds a predetermined period of 10 seconds, the motor invariably being stopped during the travel of the mine between the upper and lower control levels. The specific gravity of the mine is thus adjusted progressively by increments of decreasing amounts until the specific gravity of the mine has been adjusted to equality with the specific gravity of the surrounding water, the time required for the mine to complete an oscillation being progressively increased and the frequency of the oscillations being correspondingly decreased as the specific gravity of the mine is adjusted to the specific gravity of the. surrounding water. When this occurs, the oscillations of the mine are produced by the screw propeller alone without a change in the specific gravity of the mine by reason of the relatively short time of travel of the mine beyond each control level.

The winding of relay F, it will be noted, is connected by conductors 392 and 393 in parallel with the armature of motor M and the relay, therefore is operated whenever the motor is set in operation and releases when the operating circuit to the motor is interrupted. The manner in which relay J'is employed in connection with relays A and B to operate relay TR and thereby arm the mine after the gravity of the mine has been adjusted substantially to equality with the surrounding water will now be described, Relay TR, it will be noted, is pro.- vided with an armature 404 adapted to be actuated selectively by a pair of windings 1 and 2 to the positions shown in solid outline and in dashed outline respectively. The armature 404 is maintained in either of the operated positions thereof by a spring 405. In the event that the armature 404 of relay TR should be in the position shown in dashed outline at the time battery BA is connected to the system or should be moved to the dashed line position as the result of a shock received during the planting of the mine, a circuit is closed from positive terminal of battery BA by way of conductor 385, armature 404 of relay TR and contact 406, to winding 1 of relay TR from whence the circuit is continued by way of conductor 407, contacts 399 and 398 of switch 134 and conductor 388 to the negative terminal of battery BA thereby energizing winding 1 of relay TR and moving the armature 404 thereof to the solid line position. As armature 404 moves away from contact 406 the operating circuit to winding 1 of relay TR is interrupted and winding 1 is deenergized.

As relays A and C operated in response to the operation of the extender switch 134 during the first downward movement of the mine through the water, negative battery is momentarily applied to one end of the winding of the thermal relay G over the following circuit: negative terminal of battery BA, conductor 388, contacts 398 and 401 of switch 134, conductor 402, armature 408 and break contact of relay B, conductor 409, armature 411 and make contact of relay A, conductor 412, break con tact and armature 413 of relay F, conductor 414, winding of relay G from whence the circuit is continued by way of conductor 415 to contact 416 of're'lay TR. No current flows through the winding of relay G at this time, however, for the reason that armature 404 of relay TR is disengaged from contact 416. The foregoing circuit from the negative terminal of battery BA to the winding of relay G is interrupted by-the operation of relay F in response to the movement of armature 394 of relay C into engagement with the make contact thereof.

As relays B and D operate in response to the first upward movement of the mine beyond the upper control level within the water, the movement of armature 408 of relay B into engagement with the make contact thereof applies negative battery by way of the break contact and armature 413 of relay F to the winding of relay G until relay F operates in response to. the operation of relay D. Thermal relay G, however, is prevented from receiving a flow of current through the winding thereof at this time by reason of the disengagement of contact 416 with the armature 404 of relay T R. From the fore: going, it will be apparent that relay G cannot be operated until armature 4040f relay TR has moved to, th armed position shown. in dashed outline. I p

Relays A and C, it will be noted, are operated whenever the mine is above, the upper control limit after the extender switch 134 has been actuated and relaysB and D are operated whenever the mine is below the lower control limit, relays A, B, C, and D being unoperated while the mine is traveling between the upper and lower control limits. As the mine passes below the upper control limit during the first downward movement thereof within the water, relays A and C release. As armature 411 of relay A moves into engagement with the break contact thereof, a circuit is closed from negative terminal of battery BA by way of conductor 388, contacts 398 and 401 of switch 134, conductor 402, armature 408 and break contact of relay B, conductor 409, armature 411 and break contact of relay A, conductor 417, winding of thermal relay J, conductor 418, contact 419 and armature 404 of relay TR, conductor 3'85 and thence to the positive terminal of battery BA thereby heating the bimetallic thermal element 421 of relay I but not sufficiently for the thermal element to move into engagement with the make contact thereof. As the mine passes below the lower control limit, the operation of relay B interrupts the circuit to the heater coil of relay J at armature 408 and break contact thereof and the thermal element 421 begins to cool.

As the mine passes upwardly beyond the lower control limit of submersion relay B releases and the operating circuit to the heater coil of relay I is again closed thereby additionally heating the thermal element 421 until the mine passes above the upper control limit of submersion. When the mine has made a sufiicient number of oscillations such that relays A and B are both released during the travel of the mine between the upper and lower control limits for a period of time suificicent for relay J to close its contact, a circuit is closed from the negative terminal of battery BA by way of contacts 398 and 401 of switch 134, conductor 402, armature 408 and break contact of relay B, conductor 409, armature 411 and break contact of relay A, conductor 417, make contact and element 421 of relay 1, conductor 422, winding 2 of relay TR, from whence the circuit is continued by way of contact 419 and armature 404 of relay TR and conductor 385 to the positive terminal of battery BA thereby energizing winding 2 of relay TR and causing the armature 404 thereof to be moved to the dashed line or armed position in engagement with contacts 406 and 416. As armature 404 of relay TR moves away from contact 419, positive battery is removed from winding 2 of relay TR and the heater coil of relay J thereby deenergizing winding 2 and allowing the thermal element 421 to cool and thereby be disengaged from the make contact thereof. The mine is now armed.

Let it now be assumed that the inertia controlled contacts 347 and 348 are closed by an approaching vessel as the result of sustained translational movement of predetermined character imparted to the mine by the bow wave of the vessel or by the vessel striking the mine, as the case may be. When this occurs, a circuit is closed from the positive terminal of battery BA by way of conductor 38'5, armature 404 and contact 416 of relay TR, conductor 415, contacts 347 and 348 of the firing control mechanism 42, conductor 423, winding of relays R and K in parallel, conductor 402, contacts 401 and 398 of switch 134, conductor 388 and thence to the negative terminal of battery BA thereby operating relay R and energizing the heating coil of the thermal relay K. The operation of relay R at armature 424 thereof closes a circuit in parallel with contacts 347 and 348 of the inertia switch thereby to maintain a flow of current through the windings of relays R and K after the contacts of the inertia switch are opened. Relay K is a thermal relay and for this reason the thermal element 425 thereof does not move into engagement with the make contact of the relay until a predetermined period of time such, for example, as 5 seconds has elapsed after the contacts of the inertia switch have closed thereby to delay the firing of the mine until the mine is opposite a vulnerable portion of the vessel.

As element 425 of relay K engages its make contact, a circuit is closed from the positive terminal of battery BA by way of conductor 385, armature 404 and contact 416 of relay TR, conductor 415, armature 424 and make contact of relay R, conductor 423, make contactand element 425 of relay K, conductor 426 to the detonating device 106 from whence the circuit is continued by way of conductor 402, contacts 401 and 398 of switch 134 and conductor 388 to the negative terminal of battery BA thereby operating the detonator and firing the mine.

In the event, however, that the mine is not fired by an approaching vessel within a predetermined period of time after the mine has been launched, the mine continues to oscillate by impulses received from the screw propeller until the battery BAl is exhausted sufficiently to prevent the operation of relay F during the time that the motor operating circuit is closed. When this occurs, a circuit is closed from the negative terminal of battery BA by way of a make contact of relay A or B, as the case may be, and thence by way of the break contact and armature 413 of relay F to the heater coil of the thermal relay G from whence the circuit is continued by way of conductor 415, contacts 416 and armature 404 of relay TR to the positive terminal of battery BA thereby causing the bimetallic heater element 427 of relay G to become heated sufiiciently to engage the make contact thereof. When this occurs, a circuit is closed from the positive terminal of battery BA by way of conductor 385, armature 404 and contact 416 of relay TR, conductor 415, thermal element 427 of relay G and make contact thereof, conductor 426 to the detonator 106 from whence the circuit is continued by way of conductor 402, contacts 401 and 398 of switch 134 and conductor 388 to the negative terminal of battery BA thereby operating the detonator and causing the self-destruction of the mine when the depth regulating mechanism is rendered ineffective by the failure of the battery BA1 to continue to deliver sufiicient power to operate the motor M.

Briefly stated in summary, the present invention provides a free floating mine adapted to oscillate at a predetermined depth of submersion within a body of water in which the pump mechanism employed for adjusting the specific gravity of the mine is operated whenever the propelling mechanism is set into operation and the pump is ineffective to change the specific gravity of the mine until the propelling mechanism has operated for a predetermined period of time during the travel of the mine beyond predetermined control limits of submersion within the water, and in which the frequencies of the oscillations are reduced as the specific gravity of the mine is adjusted to the specific gravity of the surrounding water. With the mine adjusted to the specific gravity of the surrounding water further changes in the adjustment of the specific gravity during the relatively short periods of travel of the mine beyond the aforesaid control limits of submersion is prevented. The present invention also contemplates the provision of a new and improved inertia controlled mine firing mechanism comprising a compound pendulum adapted to close a pair of firing contacts only in response to a sudden lateral movement of the mine of predetermined character when the lateral movement has been sustained for a predetermined period of time whereby the mine is not fired by wave action or tidal movements of the water, provision also being made for the self-destruction of the mine when the source of power has been exhausted sufficiently to prevent further operation of the depth controlling mechanism.

While the invention has been described in detail with respect to a preferred example thereof which gives satisfactory results, it will be understood by those skilled in the art to which the invention pertains, after understanding the invention, that various changes, modifications and instrumentalities may be employed without departing from the spirit and scope of the invention and it is our intention, therefore, in the appended claims to cover all such changes, modifications and instrumentalities.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a subfloating body adapted to perform anoscillating movement about a position of equilibrium, a ballast chamber having a quantity of ballast fluid therein, a reversible pump adapted to vary the quantity of said fluid Within the chamber, means for propelling the body alternately in opposite directions about said position of equilibrium, a source of power, a hydrostatic device, means controlled by the hydrostatic device for operatively connecting the propelling means to said source of power selectively thereby to cause the body to oscillate about said position of equilibrium, means controlled by said propelling means for operating said pump whenever the propelling means is operated, and means including a valve member for preventing a change in the quantity of fluid within said chamber until the propelling means has made a predetermined number of operations in a direction to propel the body toward said position of equilibrium.

2. In a subfloating body adapted to perform an osci llating movement about a position of equilibrium below the surface of the water, means for propelling the body alternately in opposite directions, a source of power, a hydrostat device adapted to connect said propelling means to the source of power selectively in accordance with the depth of submersion of the device thereby to cause the body to oscillate about said position of equilibrium, a ballast chamber having a ballast fluid therein, a reversible pump continuously connected to said propelling means and adapted to be operated thereby in either direction in accordance with the direction of movement of the propelling means, a fluid connection between the pump and said ballast fluid, a valve member adapted to control said fluid connection, and means controlled by said propelling means for actuating said valve member to a closed position when the direction of movement of the propelling means is reversed and to an open position when the reverse movement of the propelling means has continued for a predetermined period of time.

3. In a submersible body adapted to perform an oscillating movement about a position of equilibrium below the surface of a body of water, a source of power, means including a prime mover for propelling the body successively in opposite directions about said position of equilibrium, a hydrostatic device, means controlled by said hydrostatic device for causing the prime mover to be operatively connected to said source of power thereby to urge the body selectively in either direction toward said position of equilibrium during the time the body has passed beyond certain predetermined limits of control depth and to disconnect the prime mover from the source of power when the body has moved Within said predetermined limits of control depth, a ballast fluid within said body, a reversible pump continuously connected to said prime mover and adapted to be operated in either direction thereby, a fluid connection between said ballast fluid and the surrounding water, and means including a valve member for interrupting said fluid connection until the pump has made a predetermined number of operations in a direction to urge the body toward said position of equilibrium.

4. In a device of the character disclosed for maintaining a submarine floating body in continuous oscillation about a position of equilibrium at a predetermined depth of submersion, a chamber having a ballast fluid therein, a reversible pump adapted to vary the quantity of fluid in said chamber, means for operating the pump alternately in opposite directions, and means controlled by the pump operating means for rendering the pump ineffective to vary the quantity of ballast fluid within said chamber until the pump has made a predetermined number of operations continuously in one of said opposite directions.

5. In a mechanism for adjusting the specific gravity'of a freely subfloating body to equality with the specific gravity of the surrounding water, the combination of means for propelling the body alternately in opposite directions about a predetermined depth of submersion, a ballast chamber arranged within the body and having a quantity of ballast fluid therein, a reversible pump continuously connected to said propelling means and adapted to be operated in .either direction thereby, a fluid connection between the pump and said ballast fluid, a second fluid connection between the pump and the surroundingwate'r, means for interrupting said fluid connections until the pump has operated for a predetermined period of time in each of said directions respectively and for reestablishing said fluid connections as the pump continues to operate in each of said directions respectively, a pair of check valves respectively arranged in each of said fluid connections and adapted to prevent an increase in the quantity of ballast fluid within the ballast chamber when the pump is not operated, and means for causing said check valves to open in response to a change in the pressure of the fluid within each of said fluid connections thereby to permit a flow of fluid therethrough in either direction in accordance with the direction of operation of said pump.

6. In a buoyancy control mechanism for a subfloating mine of the class described, a ballast chamber having a quantity of ballast fluid therein, a reversible pump adapted to vary the quantity of fluid Within the ballast chamber thereby to change the specific gravity of the mine, means for operating the pump alternately in opposite directions, means including a hydrostat in communication with the surrounding water for controlling the pump operating means selectively in accordance with the depth of submergence of the mine within the water, and means for rendering the pump ineifective to change the quantity of ballast fluid within the ballast chamber until the pump has made a predetermined number of operations in eac of said directions respectively.

7.. In a device of the character disclosed for controlling the buoyancy of a freely subfloating body by variations in the quantity of ballast fluid therein, in combination, a reversible rotary pump adapted to vary the quantity of said ballast fluid, a hydrostatic device, means controlled by said hydrostatic device for rotating the pump alternately in opposite directions during the travel of the body beyond predetermined control depths of submersion, a

valve member adapted to be actuated to an open position and to a closed position, means included within said valve for rendering the pump eflective to vary the quantity ofballast fluid within the body when the valve member is in said open position and to render the pump ineflective to vary the quantity of saidballast fluid when a portion of the valve establishes a fluid connection between the inlet and outlet of the pump while the valve is insaid closed position, means controlled by said pump rotating means for moving the valve to said closed position for a predetermined period of time whenever the direction of rotation of the pump is reversed, and means effective when said predetermined period of time has expired for thereafter moving the valve to said open position during the additional continuous movement of the.

pump. v

8. In a device of the character disclosed, for controlling the buoyancy of a subfloating body by variations in a ballast fluid disposed therein, a fluid connection between said ballast fluid and the surrounding water, a reversible pump adapted to force fluid through said fluid connection in either direction selectively in accordance with the direction of operation of the pump, means controlled by the depth of submergence of the body withinthe water for causing said pump to operate in each of said opposite directions selectively in succession, amovable valve member associated with the pump and adaptedto interrupt 

